Air duct jack



| N. REUTER 3,017,174

AIR DUCT JACK Filed March 4, 1959 Jan. 16, 1962 INVENTOR.

A T TOPNEY! United States Patent i 3,017,174 A DUCT JACK Luke N. Renter, 116 N. Fond du Lac Ave, Menomonee Falls, Wis. Filed Mar. 4, 1959, Ser. No. 797,071 Claims. or. 269-126) This invention relates to an air duct jack.

The improved jack is designed to support a duct or pipe temporarily until it can be connected and hung from the ceiling joists.

Exposed and ventilating ducts are frequently rectangular in cross section and, assuming that they are spaced materially below the joists, it becomes important to orient the ducts so that they will be horizontally parallel to the joists. Ordinarily the services of at least two men are required to erect duct work. Using one or more jacks in accordance with the present invention, it is easily possible for a single man to make the installation.

A clamp has relatively movable jaws for engaging a joist and has a rigid straight edge engageable with the lower margin of the joist for fixing the clamp at right angles to the joist. An adjustable arm carried from the clamp is thereby positioned parallel to the under side of the joist so that a duct mounted on the arm will necessarily be horizontally true.

In the drawings:

FIG. 1 is a perspective view looking upwardly at a duct jack embodying the invention as the jack appears when in use.

FIG. 2 is a view on an enlarged scale showing the jack partially in side elevation and partially in section, a joist engaged thereby being shown in section.

FIG. 3 is a further enlarged detail view in perspective showing the clamping jaws spread to receive the joist, the jack post being fragmentarily illustrated.

FIG. 4 is a fragmentary view in perspective showing the upper end portions of the clamping jaws used in a modified embodiment.

The duct 5 is to be temporarily supported at a distance below the lower margins 6 of joists 7. To support the duct temporarily in the desired position until it can be fixed on the usual suspension straps (which must be fabricated to fit the installation), my improved jack comprises a jack post 8 upon which the duct supporting arm 9 is longitudinally adjustable, the jack post being supported from a given joist 7 by means of a clamp including relatively movable jaws 10 and 11.

Each of the clamping jaws desirably comprises a channel. One or both of the channels may have its flanges marginally serrated as shown at 12 to provide teeth for causing the jaws to engage more securely the side surfaces of a joist with which the clamp is engaged. In FIGS. 2 and 3, only the jaw 11 is marginally toothed. FIG. 4 shows a construction in which the jaw 10' is also toothed. This is intended to be typical of modifications which may be made to include or omit teeth in one or both jaws as desired.

Side arms 15 welded to jaw Ill as at 16 support a pintle 17 which passes through the side flanges 18 of jaw 11 to provide a pivotal connection upon which jaw 11 is movable toward and from jaw 10, the spacing between jaws being such that when the jaws are parallel they will be in secure engagement with an intervening joist. Any desired means may be used for closing jaw 11 toward jaw 10, the device illustrated being a screw 20 having an operating handle 21 and a collar 22 externally engaged with the web 23 of the pivoted jaw 11. The screw passes through a nut 24 welded to the web 25 of the relatively fixed jaw 10. A compression spring 3,017,174 Patented Jan. 16, 1962 26 is desirably interposed between the webs of the respective channels which constitute the jaws 10 and 11 to facilitate the separation of the jaws toward joist-receiving position when the screw 20 is turned reversely following a clamping operation.

The jack post 8 may be fastened to the clamp in any desired manner. In the preferred construction, it is held by a weld at 28 to the relatively fixed jaw 10.

A pipe supporting arm 9 is welded at 29 to a sleeve 30 which fits telescopically upon the jack post 8 and is provided with a set-screw 31 whereby it may be fixed in any position on the post. A brace 32 is desirably used to extend from the bottom of sleeve 30 to a point at 33 outwardly of the sleeve. This assures that the arm 9 will always be at right angles to the jack post 8.

In order that the jack post may also be at right angles to the lower margin 6 of the joist, a straight edge 35 is provided by the flange 34 of an angle 36 welded at 37 to the side flanges 33, 39 of the channel-shaped jaw 10.

Before the jaws are tightened on a joist, the straight edge 35 is positioned securely into engagement with the lower margin of the joist. The movable jaw 11 is then moved by the adjusting means to a position of engagement with the joist, whereupon the joist will be clamped between the arms 10 and 11 in a vertical position determined by the straight edge 35. This will assure that the jack post 8 will be at right angles to the joist and that the arm 9, in turn, will be horizontal and parallel to the joist. Consequently the air duct 5 supported on the arm 9 at the desired level as determinedby the position of sleeve 30 on the jack post will be properly oriented for connection into the duct system. As many pipe jacks as may be needed will be used to support the pipe until the connection and support thereof is perfected.

I claim:

1. A duct jack for use with an exposed joist in supporting a duct for installation beneath said joist, said jack comprising an upright jack post, an upright joist-engaging jaw connected with the upright of the post 'and constituting an upward extension thereof, a complementary jaw extending vertically in spaced relation to the jaw first mentioned, means for mounting the complementary jaw for movement to and from the jaw first mentioned, means for effecting such movement of the complementary jaw to and from clamping engagement with a joist intervening between said jaws, means extending transversely between said jaws and above which said jaws are open to receive a joist, the transversely extending means defining a straight edge adapted to be engaged with the lower margin of a joist with which said jaws are in clamping engagement, a member vertically adjustable along the post, and a duct-supporting arm projecting laterally from the member to partake of adjustment thereof.

2. The device of claim 1 in which the first mentioned jaw comprises a channel having flanges across which the means defining the straight edge is disposed, said last mentioned means being connected with said flanges.

3. The device of claim 1 in which the first mentioned jaw comprises a channel having flanges across which the means defining the straight edge is disposed, said last mentioned means being connected with said flanges, said complementary jaw comprising a channel having flanges directed toward the flanges of the first mentioned jaw and provided with marginal serrations constituting teeth for joist engagement.

4. The device of claim 1 in which the means for adjusting the complementary jaw comprises a cranked screw extending through the complementary jaw and having a jaw-engaging shoulder abutting the complementary jaw, the first mentioned jaw having a nut with which said screw is engaged, and a compression spring encircling the screw between said jaws and acting on the complementary jaw in a direction to release it from joist engagement, said screw being adapted to engage the complementary jaw with a joist with which the first mentioned jaw is in contact, and to compress said spring in so doing.

5. A duct jack for use with an exposed joist to support a duct installation beneath said joist, said jack comprising a first jaw having the form of a channel with lateral flanges, an upright jack post having its upper end positioned between said flanges and connected with said first jaw to hold said first jaw in an upright position as an extension of said post, bracket means connected with the first jaw and projecting laterally therefrom past said post, a second jaw in pivotal connection with said bracket means and comprising a channel having spaced flanges directed toward the flanges of the first mentioned jaw, and means providing a straight edge connected across the flanges of the first mentioned jaw above said bracket means and in a position to engage the lower margin of a joist with which the respective jaws are clampingly engaged, a nut connected with the first mentioned jaw beneath, the means providing a straight edge, a screw extending through the movable jaw and in threaded engagement with the nut and provided with a shoulder externally engaging the movable jaw, said screw having a crank for its rotation to efiect movement of the movable jaw toward the first mentioned jaw, a compression spring encircling the screw and confined between said jaws, a sleeve adjustable on the post and provided with means for fixing its position thereon, and a duct-supporting arm projecting laterally from said sleeve.

References Cited in the file of this patent UNITED STATES PATENTS 305,776 Amstutz Sept. 30, 1884 783,031 Fell Feb. 21, 1905 1,153,320 Klenck Sept. 14, 1915 1,288,199 Rice Dec. 17, 1918 1,784,244 Morris Dec. 9, 1930 2,468,358 Clark Apr. 26, 1949 2,606,583 OConnor Aug. 12, 1952 2,889,145 Hoffman June 2, 1959 FOREIGN PATENTS 684,683 Great Britain Dec. 24, 1952 

